The dentin is composed mainly of hydroxyapatite (Ca10(PO4)6(OH)2). In the mouth, there is an equilibrium between dissolution (demineralization) of phosphate ions and calcium ions and crystallization (remineralization) of calcium phosphate or hydroxyapatite. At the initial stage of tooth decay, white spots usually appear in the transparent enamel layer of the tooth. If fluoride ions or calcium ions are caused to exist on the tooth surface at this stage, remineralization is promoted by these fluoride ions or calcium ions, resulting in the disappearance of these white spots and recovery of transparency of the enamel layer.
When both fluoride ions and calcium ions are incorporated in one composition in advance, however, they react with each other to form calcium fluoride particles having too large a particle size to be taken readily into the tooth. This results in the problem that a tooth remineralization-promotion effect is not possible.
To overcome this problem, a two-component type oral hygiene product has been proposed (Japanese Patent Application Laid-Open No. Sho 52-61236) in which two components are contained in respective containers and, upon use, they are mixed as needed. The toothpaste disclosed therein is however inconvenient, because the two components filled separately in the respective tubes must be mixed upon use.
Japanese Patent Application Laid-Open No. Sho 53-41441 discloses “a toothpaste composed of at least two components which are mutually reactive and are maintained separately in one dispensing container capable of discharging the content therefrom via a closable orifice”. Japanese Patent Application Laid-Open No. Sho 58-219107 discloses a bottle having two compartments as an embodiment physically separating a calcium ion substance and a fluoride ion substance. Japanese Patent Application Laid-Open No. 2001-247439 discloses “a complex toothpaste comprising a first toothpaste component containing tricalcium phosphate as a main effective ingredient; a second toothpaste component containing a fluoride compound as a main effective component; and an integrally-formed container having a plurality of chambers needed to hold these two components separately and a discharge port required for discharging these two components therefrom. In each of the above-described documents, however, no reference is made to discharging of a predetermined amount of each composition filled in the chamber or compartment.
On the other hand, it is difficult to stably discharge the desired amounts of the two compositions filled in the respective chambers or compartments, because they have different components and therefore have different physical properties. In some cases, imbalance in the discharged amount between these two compositions occurs and the amount of one of them is excessively large, while that of the other one is small. It is therefore difficult to stably discharge predetermined amounts of these two compositions every time they are discharged. In particular, when one of the compositions contains granules and the other one does not, the above-described problem is pronounced owing to a difference in the physical properties attributable to the presence or absence of the granules, making it difficult to simultaneously and stably discharge desired amounts of these two compositions whenever they are discharged.
The present invention relates to a toothpaste containing two compositions prepared separately in advance as respective compositions and filled separately in a tube container capable of discharging a mixture of the compositions each in a predetermined amount, said two compositions, when mixed in advance, being not able to achieve the intended object of the invention.